Melt the butter in a large saucepan and sauté everything except the mussels and the liquids over medium heat until lightly browned. Take your time with this part to achieve a nice caramelization of the onions.

Add the mussels, cider and lemon juice and simmer until the mussels pop open. Stir in the crème fraîche and serve immediately with crusty bread (or, if you are hardcore, French fries) to soak up the sauce. To drink: the rest of the bottle of cider. Yum!